Hot melt, pressure sensitive adhesive formulations find many applications, one of which is as a pressure sensitive adhesive for recloseable fastening systems for hygiene absorbent products. Hygiene absorbent products (or HAPs) include diapers, adult incontinence products, swim-wear diapers, and training pants. Hygiene absorbent products are typically comprised of layers of non-woven fabrics, comprising natural or synthetic polymer fibers and films made from thermoplastics polymers. HAP reliability (i.e., prevention of leakage), comfort (i.e. softness and form-fit during use), and longevity (e.g., reclose-ability after opening (to check for exudates)) depends upon the ability of the “pressure sensitive adhesive fastening tab” to adhere only to the tab landing zone, while not sticking to human skin, other HAP parts, or foreign materials such as contaminants. HAP reliability, comfort, and longevity diminish when the HAP fastening system adheres to foreign materials. The fastening system's adherence to contaminants or foreign objects weakens the bond strength, and may compromise the fastening system altogether.
Similar to HAPs, other products, such as protective medical garments and medical drapes, require cohesive fastening systems to prevent contamination of blood-borne pathogens to the medical garment wearer (e.g. surgeons and medical assistants), and to provide isolation of the patient's wound or surgical sites for selected medical drapes. Conventional pressure sensitive adhesive tabs (such as diaper tabs), mated together, exhibit low peel force for repositionability, yet high shear in order to keep the HAP closed. However, conventional diaper tabs also adhere to foreign materials, which degrade reliability. Mechanical fasteners, such as hook and loop fasteners, are problematic, because they are rough on the skin, and they are also expensive to manufacture.
A need exists for a pressure sensitive adhesive composition that adheres only to itself (cohesive), while simultaneously providing (i) low T-peel strength (for example, less than 10 N/in) and low tack (does not form a quick bond to substrates other than itself), while (ii) maintaining high lap shear (for example, greater than 1 hour). A need further exists for fastening systems utilizing cohesive layers formed from such a composition. These needs and others have been met by the following invention.